Chemical Agent Exposure Scenarios

Objectives

• Describe boiling point, chemical reactivity, corrosivity (pH), and flammable range.
• Describe the lower explosive limit (LEL,) the upper explosive limit (UEL), and flash point.
• Describe ignition temperature, particle size, persistence, and physical states of matter.
• Describe radiation (ionizing/non-ionizing) and specific gravity.
• Describe toxic products of combustion, vapor density and pressure, water solubility, and physical/chemical changes.
• Describe types of radiation, including alpha particles, beta particles, gamma rays, and neutrons.
• Describe the differences between contamination and secondary contamination.
• Describe the differences between exposure and contamination, exposure and hazard, and infectious and contagious.
• Describe the differences between acute and chronic effects, and between acute and chronic exposures.
• Describe nerve, blister, and choking agents, and irritants in terms of weapons of mass destruction.
• Describe routes of entry for hazardous materials in humans.

Chemical and Physical Properties

• Chemical and physical properties are characteristics of a substance.
• These properties should be understood for hazardous substances and WMD (Weapons of Mass Destruction).
• Chemical and physical properties are the basis of good response decisions.
• Measurable properties include vapor density, flammability, corrosivity, and water reactivity.

State of Matter

• State of matter identifies a hazard as solid, liquid, or gas.
• State of matter helps predict a substance's behavior, including how it will escape a container or why a container failed.
• State of matter influences the incident's duration.
• Duration, in turn, informs the emergency response plan.

Physical Change

• Physical change can occur when chemicals are subjected to heat, cold, or pressure.
• BLEVE (Boiling Liquid/Expanding Vapor Explosion) occurs when pressurized liquefied materials inside a closed vessel are exposed to high heat.
• BLEVE results in physical change from liquid to gas such as with propane and butane.
• The expansion ratio describes the volume increase that occurs.

Chemical Reactivity

• Also referred to as a chemical change.
• Chemical reactivity is the ability to transform at a molecular level, usually releasing some form of energy.
• Examples of chemical reactivity include steel rusting and wood burning.

Critical Characteristics of Flammable Liquids

• Flash point, ignition temperature, and flammable range are critical characteristics.
• Only substances in a gaseous or vapor state will combust.
• Solids and liquids produce vapor, then ignite.

Flash Point

• Flash point is the minimum temperature at which ignition results in a flash fire, and the fire will extinguish once the vapor fuel is consumed.
• Responders should be mindful of ignition sources at flammable/combustible liquid incidents.
• Gasoline has a flash point of -45°F.
• Low flash point indicates high ignition temperatures and vapor pressures (e.g., gasoline, ethyl alcohol, acetone).
• High flash point indicates low ignition temperatures and vapor pressures (e.g., #2 grade diesel fuel).

Fire Point

• Fire point is the temperature at which sustained combustion of vapor occurs.
• Fire points are usually slightly higher than flash points.

Ignition Temperature

• Ignition temperature is also known as autoignition temperature.
• Ignition temperature is the temperature at which heated fuel ignites and continues to burn.
• Ignition temperature does not need an external ignition source.

Flammable Range

• Flammable range is the concentration (%) of flammable vapor and air needed for a fuel/air mixture to burn.
• Flammable range is defined by the lower explosive limit (LEL) and the upper explosive limit (UEL).
• More dangerous material has a wider range.

Vapor Pressure

• Vapor pressure pertains to liquids inside a closed container and may be expressed in pounds per square inch (PSI), atmospheres (atm), torr, or millimeters of mercury (mm Hg).
• Vapors released from any liquid's surface must be contained in order to exert pressure.
• Vapor pressure is influenced by ambient temperature: a high temperature increases vapor pressure, and a low temperature decreases it.
• Vapor pressure causes liquids to evaporate when released; high vapor pressure evaporates quickly, and low vapor pressure evaporates slowly.

Boiling Point

• Liquids continually give off vapors.
• Molecules must overcome the downward force of atmospheric pressure.
• If maintained, all liquid will turn into gas.
• Atmospheric pressure pushes down at 14.7 psi.
• Water boils at 212°F.

Vapor Density

• Vapor density is the weight of vapor compared to the weight of air and is expressed numerically.
• Air has a set vapor density of 1.0
• Vapor density > 1.0 is heavier than air, vapor density < 1.0 = lighter than air.
• Vapor density affects a gas' behavior during release.
• “4H MEDIC ANNA” identifies lighter-than-air gases.
• Vapors with density < 1.0 will rise, vapors with density > 1.0 will sink.

Specific Gravity

• Specific gravity compares the weight of a liquid chemical to the weight of water.
• Water has a specific gravity of 1.0.
• Materials with specific gravity less than 1.0 float on water.
• Materials with specific gravity greater than 1.0 sink.
• Most flammable liquids float on water.
• Gasoline will float on water, carbon disulfide won't.

Water Solubility

• Water solubility is a substance's ability to dissolve in water.
• Water is most often used to extinguish fires, but it reacts violently with some chemicals, e.g., sulfuric acid, metallic sodium, and magnesium.

Corrosivity

• Corrosivity is a material's ability to cause damage to skin, eyes, other body parts, clothing, and rescue equipment.
• Corrosive chemicals should be taken seriously because they require unique response tactics.
• Two types of corrosive chemicals are acids and bases.
• Corrosivity is defined by pH.
  • Acids have a pH less than 7.
  • Bases have a pH greater than 7.
  • A pH of 7 is neutral.
  • pH < 2.5 or > 12.5 is considered strong

pH Scale

• Examples of acids, from pH 0-6:
  • Hydrochloric acid - 0
  • Lemon Juice - 1
  • Stomach Acid - 2
  • Vinegar, cola, beer - 3
  • Tomatoes, champagne - 4
  • Peat Bogs or Black coffee - 5
  • Urine - 6
• Examples of bases, from pH 8-14:
  • Saliva and distilled water - 7pH
  • Human Blood and Seawater - 8
  • Baking Soda - 9
  • Great Salt Lake - 10
  • Ammonia - 11
  • Bicarbonate of soda - 12
  • Oven Cleaner - 13
  • Sodium Hydroxide (NaOH) - 14

Toxic Products of Combustion

• Materials decompose under heat, resulting in hazardous chemical compounds.
• Smoke may contain soot, carbon monoxide/dioxide, water vapor, formaldehyde, cyanide compounds, and nitrogen oxides.

Radiation

• Radiation is energy transmitted by electromagnetic waves or energetic particles.
• Sources: Sun, soil, X-rays, occupational exposures in the field.
• The amount of radiation absorbed and the exposure time affect the degree of damage.

Alpha Particles

• Have weight and mass.
• Travel less than a few centimeters.
• Protection methods: staying several feet from the source, using HEPA filters on a respirator, and using a self-contained breathing apparatus (SCBA).

Beta Particles

• More energetic than alpha particles.
• Pose a greater health hazard.
• May redden (erythema) and burn skin.
• May be inhaled (wear SCBA).
• Can travel 10 to 15 feet in open air.
• Are considered ionizing radiation.
• Cannot pass through most solid objects.

Ionizing Radiation

• Can cause changes in human cells.
• Can lead to cancer.
• Examples: X-rays, gamma rays.

Non-ionizing Radiation

• Comes from electromagnetic waves.
• Does not have sufficient energy to change human cells.
• Examples: Sound waves, radio waves, microwaves.

Gamma Radiation

• Pure electromagnetic energy.
• Most energetic radiation responders may encounter.
• Passes easily through thick, solid objects.
• A form of ionizing radiation, it can be deadly.
• SCBA will not provide protection.
• Neutrons can create gamma radiation.

Hazard and Exposure

• Hazard: A material capable of causing harm.
• Exposure: A process by which people, animals, the environment, and equipment come into contact with a hazardous material.

Contamination

• Contamination is residue from released chemical such as through the process of residue removal via decontamination.
• Secondary contamination is transferred from the source by direct contact.
• PPE protects if contact cannot be avoided, but does not allow unlimited contact.

Weapons of Mass Destruction

• TRACEMP is a mnemonic device for the types of damage caused by WMD.
  • T - Thermal
  • R - Radiological
  • A - Asphyxiation
  • C - Chemical
  • E - Etiological (anthrax, plague, smallpox)
  • M - Mechanical
  • P - Psychogenic

Nerve Agents

• Nerve agents enter the body through the lungs or skin, disrupt the central nervous system, and may cause death or serious impairment.
• Dose absorbed dictates the extent of damage.
• Examples of nerve agents include Sarin and VX.
• Signs/symptoms can be remembered with the acronym “SLUDGEM."
  • S - Salivation
  • L - Lacrimation (tearing)
  • U - Urination
  • D - Defecation
  • G - Gastric disturbance
  • E - Emesis (vomiting)
  • M - Miosis (constriction of the pupil)

Blister Agents

• Blister agents are also known as vesicants.
• Blister agents cause blistering of the skin, and interact in harmful ways with the body.
• Examples of blister agents include Sulfur mustard and Lewisite.

Blood Agents

• Blood agents disrupt oxygen transfer from blood to cells.
• Blood agents can be inhaled, ingested, or absorbed through skin.
• An example of a blood agent is cyanide compounds.
  • Typical signs/symptoms include vomiting, dizziness, watery eyes, and deep/rapid breathing.

Choking Agents

• Choking agents inhibit breathing and are skin irritants.
• Choking agents have an extremely irritating odor.
• Choking agents are intended to incapacitate, but may kill. May cause pulmonary edema ("dry drowning").
• Examples of choking agents include Chlorine, phosgene, and chloropicrin.

Irritants

• These riot control agents cause pain and burning sensation when being exposed to skin, eyes, and mucous membranes.
• Irritants are used to briefly incapacitate a person or group and are the least toxic of the WMD groups; decontaminate with water (effects are designed to wear off).
• An example of an irritant is Mace.

Convulsants

• Cause convulsions or seizures.
• Even small exposure can be fatal.
• Examples include sarin, soman, tabun, and VX, and also some organophosphate and carbamate pesticides.

Harmful Substances -- Routes of Entry Into Body

• The routes of entry are inhalation (through lungs), absorption (through skin), ingestion (through gastrointestinal tract), and injection (through cuts or breaches in skin).

Inhalation

• Hazardous materials and WMDs, corrosive materials, and particles can pose hazards via inhalation.
• SCBA offers excellent protection.
• Infectious and contagious organisms also present a hazard such as with Anthrax.
• Air-purifying respirators protect against certain airborne chemical hazards.
• Air-purifying respirators are more comfortable and allow longer work periods.

Absorption

• Enters through Skin, eyes, nose, mouth.
• Asphyxiants may form, causing suffocation.
• Some agents are carcinogens.
• Aggressive solvents such as paint stripper and hydrofluoric acid.

Ingestion

• Chemicals enter body through GI tract
• May occur when rotating out from emergency.
• After hazardous work, wash before drinking or drinking/eating.

Injection

• Harmful substance exposure through cuts, abrasions, or open wounds.
• Address these before reporting for duty.

Chronic Health Hazards

• Appear after long-term and/or multiple short-term exposures .
• Exhibits target organ effect, such as with abestosis.

Acute Health Effects

• Occur after short, acute exposure.
• Examples include acid burns, breathing difficulties, formaldehyde induced skin irritation.

Toxicity

• Indicates the degree to which something is toxic or poisonous, substance's adverse effects, lethal dose (LD,) lethal concentration (LC) as per OSHA descriptions.

Key points

• It is important to know the chemical and physical properties of substances in order to make informed response.
• Hazards should be understood before responding, to minimize potential for exposure and to avoid contamination
• Hazardous substances and Weapons of Mass Destruction enter the body through inhalation, ingestion, injection, and absorption
• HAZMAT may be used as Weapon of Mass Destruction such as nerve, blood, blister and choking agents as well as Irritants and convulsants.
• HEPA filters and SCBA protect lungs.
• Wear protective gear to avoid chronic health effects after years of exposure!

Test your knowledge of chemical agent exposure. Scenarios cover symptoms, exposure routes, and agent identification. Sharpen your understanding of emergency response protocols.